Safety device for power-presses.



W. BRETSNYDER.

SAFETY DEVICE FOR POWER PRESSES.

APPLICATION FILED 050.22. 1913.

1 21 319, Patented Jan.16,1917.

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SAFETY DEVICE FOR POWER PRESSES. APPLICATION FILED 056.22. 1913.

Patented Jan. 16, 1917.

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SAFETY DEVICE FOR POWER PRESSE S.

Patented Jan. 16,1917.

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WILLIAM BRETSNYIDER, OF CHICAGO, ILLINOIS.

SAFETY DEVICE FOR POWER-PRESSES.

Application filed December 22, 1913.

T 0 all whom it may concern Be it known that 1, WILLIAM BRETSNYDER, of Chicago, Illinois, a citizen of the United States of America,'have invented a certain new and useful Improvement in Safety Devices for Power-Fresses, of which the following is a specification.

My invention relates to safety appliances, adapted to hand-fed power presses having a stop mechanism; andxl illustrate it in its application to a'type of machine commonly known as a power-punch-press.

My primary object is to render'perfectly safe the operation of such presses. I know that heretofore there have been projected various contrivances intended to accomplish'in part-the objects which I have in view. The devices heretofore brought out and perfected do not render the whole operation absolute proof against the possibility of injury to the operator. It is well known to any one skilled in the art, that a prolific source of accidents in the operation of such a machine is the attempt upon the part of the operator to put his hand into the ma-- chine to correct something just prior to or during the descent of the punch, or failure to withdraw the hand after placing the stock. Also injuries to the machine and dies occur by reason of work improperly fed or set, and no ability to prevent the operation of the machine without endangering the operator.

My main offset is to accomplish perfect results at this point, which basically differentiates my invention from all others. In the application of my invention the descent of the punch is always under the positive control of the operator, and is automatically controlled in the event of the operators neglect. The operator is informed in advance that the machine is about to operate. As the feeding of the machine involves the intrusion of the hand between the punch and the dies, if his hands are in any proximity to the danger Zone, the maintenance of the hands within the danger-zone absolutely prevents the descent oftue punch; this condition exists and continues even though the needle covers the whole area of its travel.

A collateral object which I desire to ac complish is the absolute protection of the hands, even though the hands-be upon the die and .nedietciy under the punch. 1' desire to accoinpiish automatic protection in th =rtion the machine, such that the Specification of Letters Patent.

Patented Jan. 16, 1191?.

Serial No. 808,192.

operator cannot suffer injury to his hands under any conditions in the operation of the machine. As a result, I meet all fear in the operator, and tend to increase the output in the operation of such machines. As a result, further, I maintain a steady stroke in the foot operation, thus eliminating the ordinary nervous kicking of the press.

The invention consists generally in means which inform the operator the instant any one starts to operate the machine. In advance of the operation of the crank-shaft a lever is presented in front of the operators hands, which controls the whole process of the operation. In unison therewith, means such as will automatically prevent any possibility of successive strokes of the press after one revolution, until the treadle comes to its full normal position. Collateral with this, I render it impossible for the press to operate for a second stroke during any of the time the treadle is covering the area of its travel or if held at its extreme limit, thus making it wholly impossible to have an accident resulting therefrom.

The invention is applicable to various types of presses and also to various types of clutch mechanism.

This invention is so constructed that it can easily be attached to, or detached from, an ordinary type of power-punch-press, or similar mechanism.

In the accompanying drawings, Figure 1 shows the mechanism as attached to the ordinary power-punch-press; Fig. 2 is an enlarged side-view detail of the mechanism at rest, with section cut-away. Fig. 3 shows the position of the mechanism in operation, with the treadle down, the hand under the punch, the lever intercepted in its travel, the toggle broken, the connection between the clutch-pin and treadle elongated in its travel; showing how treadle action is nullified and action on clutch pin prevented. Fig. 4 shows a side view of the mechanism the instant prior to action taking place on the clutch-pin, the treadle partly depressed, the lever raised, and the clutch-pin intact. The position of a segmental arc is shown in relation to the trip-rod, serving as a bar to block the lever when in an upright position during the downward travel of the trip-rod.-

ing a successive stroke. Fig. 6 is a frontview showing the detail of the mechanism at rest. Fig. 7 is a detail of the special devices which operate to prevent the drawing of the clutch-pin; also preventing a successive stroke. Fig. 8 is a detail of the same mechanism showing the position of the parts immediately subsequent to the descent ofv the press plunger; also as it appears when the lever has been intercepted, allowin r the clutch-pin to remain in its position of rest, also as it appears when the clutch-pin has been returned. to its position of rest by the collapsing of thetoggle and links. Fig. 9 illustrates a detail of a clutch assemblage in connection with the lever, an arc to automatically control the trip-rod; also showing the angle arm, for limiting the travel of the lever and arc. Fig. 10 is a detail of the position of the lever clutch members when treadle is depressed to its full limit for stroke of plunger; also showing the location of the segmental arc stop. Fig. 11 is a cross section of the collar and trip-rod, with a broken section of the trip-lever swiveled upon it. Fig. 12 is a detail of a bolster bed with the lever attached. Fig. 13 is the lever assemblage.

I do not limit myself to the strict form and type herein shown, but illustrate the principle as applied to this type of press. To those familiar with the art, it is known that the ordinary punch-press is set in operation by means of a treadle which is maintained in an elevated position by a spring; it is pressed downward with the foot of the operator; this'treadle has a connection between it and a clutch mechanism assembled on the eccentric shaft, which operates the plunger; this clutch mechanism unites and engages the power driven pulley andthc eccentric shaft by some mechanism adapted tocontrol its individual operations. Ordinarily if the operator maintains the pressure upon the treadle the eccentric shaft will continue to' revolve; if he desires to stop the revolutions of the crank-shaft after each revolution he must release the pressure upon the treadle. Thistripping of the lever to maintain individual strokes involves a nervous activity upon the part of the operator. It is impossible for him to regulate such pressure under all conditions without endangering undesired successive strokes of the punch. It is further known that watching the descent of the plunger tends to confuse the other activities. Expert operators have an inclination to fail to withdraw the hand following the pressure upon the treadle; or,'in an almost involuntary action, attempt to thrust the hand into the machine (after the plunger has begun to descend) to correct some defect in the feeding of the press. It is also well known that the strain upon the leg, impressing the treadle, tends to induce a successive stroke practically on the pinion e.

without the volition of the operator; resulting in the descent of the plunger while the hands are in the danger zone.

In the accompanying drawings, in Fig. 1, I illustrate a common type of power-press in which A are the supporting legs, carrying a frame B; C is a pulley-wheel moving upon an eccentric shaft D; assembled on the shaft. D is a master clutch for controlling the revolutions of the eccentric shaft, in connection with the clutch-pin M. F is a treadle attached to a bearing at G. H is a plunger brought into action by the revolutions of the pulley-wheel C operating on the eccentric-shaft D. I is a bolster plate. J is a spring one end of which is attached to the treadle F, the other end to a frame A; the said spring is intended to sustain the treadle in an elevated position and to return the operative parts of the toggle and links to their normal position of rest. K is a fixed pivot point projecting from the side of the frame B and located so as to be the pivotal point for. the bell-crank-lever N, operating the clutch mechanism. L is a point on the bell crank-lever N, to which is pivotally attached the mechanism connecting the clutch operating mechanism with the treadle.

Between the treadle at E and the clutch lever L, I provide a mechanism as follows :Pivotally attached to the treadle, is a connecting rod a an adjustable collar (1 has pivotally attached thereto at b one end olfi a connecting rod (2. the other end of said rod a being pivotally attached to an arm 9 which is an integral part of a clutch member h. The'connecting rod a has an adjustable device b somewhat adjacent to b for regulating the length of rod a, when the bed of the press is inclined out of a horizontal position. Connecting rod a passes through a block 0 and slidably operates therein, as hereinafter shown; its extension passing slidably through a block 0?. In the block 0, I provide an elongated slot 0 Therein I provide a pin 0 -which pin passes transversely through and is fixed in the rod a, and moves freely in said slot. The rod a passes slidably through the block d at d, the block d being pivotally attached to the bell-crank-lever at L. I further provide a fixed pivot-pin e extending at right angles from the frame B and attached to the same at f. On said pin, I assemble clutch members It and 71. the said clutch members being held in position by the collar 7L2 adjustably fixed to the pin e by the set screw h the members of the clutch are sustained in engaging relation by the compres sion spring 11 and an adjustably fixed collar The clutch member it has an arm h extending therefrom, the said arm 72, having a hole at g transverse thereof for the pivoting of the operating rod a The clutch member 2} having'integral therewith and extending upward therefrom, an. arm 71, from the reverse side thereof, extending downwardly, an arm h. The said arm k terminates in an are k", said arni k and are h being adjustable at 7L7. The arm 11, is transversely perforated at its lower terminus. Integral with the collar if I provide an arm it turned at an angle and projecting over and beyond the area of travel of the clutch arm IL -adapted to regulate and limit the travel of the arm k and the lever m. The are it of the arm h travels under the offset 3% of the trip-rod s. T preferably provide the ofiset at s but it may be at any convenient point at or above pivotal point r v I provide a connecting rod is, one end of which is pivotally attached to the arm 72, at point 75 the other end of which is pivotally attached at k to an oscillating rocker arm Z. Said connecting rod is has means 10 between the said points of sus pension for adjusting the length of said connecting rod k. The rocker arm Z is adjustably attached to a shaft n which said shaft is loosely journaled in bearings 01, and n these hearings being integral with a frame 0, which said frame is adapted to fit upon the bolster bed of the press and.

is adjustably attached thereto by set screws 0 Adjustably attached to the shaft n I provide a lever m.

Between blocks 0 and d, and connected therewith, I provide a combination of links and toggle; said device is composed primarily of four links r pivoted to each other at 7*, r 7", and 1- at r the links PlXOiIGCl at this point are hung on a pinion fixedly attached to block d; at 1* the links pivoted at that point are hung on a pinion fixedly attached to block 0. From the point r to the point 1', I depend a toggle composed of two links 7* and r these said toggle links have an offset 1' on each, adapted to form a stop for the ends 1' on the links 1* and 7', and check their downward travel at center; the toggle-links r and r are pivoted at W; the toggle link rat its point of attachment at r*,is perforated with an elongated slot 7*, to afford lostmotion as also to provide an instantaneous brace of lock. I further provide a trip-rod 3 having one end pivoted on the pin 7 its other end threadedly adapted to receive the adjustable set nut 8 a set off .9 at 1' or a point above, forms a shoulder. I provide a triplever t pivotally mounted on the pivot-pin K. ()ne end of said lever is swiveled to a collar 25 surrounding the rod 8 at or near its threaded terminal; the opposite end extends to a point t where it is in contact with the collar u fixedly assembled on the crank-shaft D. At t I provide a coiled spring, one end of which is attached to the trip-lever t, the other end to the clutch casing, which tends to maintain the trip-lever 2f in contact with the collar u at the point I provide a lug 0; extending outwardly from the collar u and adjusted to come into contactin the revolution of the shaft with the trip-lever 25.

A press of the type described ordinarily has spring means for maintaining a clutchpin in locked contact with the eccentric shaft, which said means also serve to return it to that position when the clutchpin has been withdrawn and the withdrawing power released. This is no part of my mechanism. The function of the links and toggle herein described is to provide a means whereby the connection be tween the treadle and the clutch pin lever may be elongated at the will of the operator,.or maintained as a rigid unit, in the operation of the machine. 'When in a normal position of rest the links are maintained in rigid relation by the toggle extending across from 1- to r. This rigid positionholds the block 0 in a fixed relation to block d. The rod a being free to move in block cl at al it merely adds to this rigidity. If the rod 8 is intercepted in its travel by the are 71, the block 0 carrying with it rod a is free to continue a downward course, it being free to move downward through block 0?. The links of the toggle pinioned at r are maintained in a fixed position with relation to (Z unless obstructed by are 71, which obstruction causes the collapsing of the toggle and the links. The elongation thus produced between the treadle and the clutch-pin is equal to the travel of the treadle and thus neutralizes any action of the treadle. When the treadleis released and forced to its normal position by means ofspring J, all the links are forced back to their initial position and the toggle assisted by the slot 1" at r with the rod 8 drops of its own weight into the initial lockedposition. The rod 8 is limited in its downward travel by the shoulders r at 7' When the eccentric shaft starts to perform a revolution and the lug v strikes the lever 23 it'causes the collar F-attached thereto-to strike the nut s and raise the rod 8. In so doing, it accomplishes the same result as when the are It is caused to obstruct the downward travel of rod swhen said are k is held in such obstructive position by any force in contact with lever m. In the one case, it serves to prevent action of the treadle'on the clutch-pin; and in the other case, it automatically serves to permit the clutch-pin to return to its initial osition and prevent a successive stroke 0 the press. The loose play provided at 0 permits the are k to pass out of the line of travel of s an appreciable time before the clutch-pin M is withdrawn. When this po- .arms extending therefrom.

sition is attained, and the clutch-pin is about to be withdrawn the lever plate m is vertically between the operator and the punch. If any force is brought to bear upon the lever plate m, the are it is instantly stopped and held in the path of travel of the shoulder 3 thus preventing action upon the clutch-pin.

When the machine is in the normal position of rest, the lever is parallel with the bed of the press, and is so related that, to get his hands in any position under the punch, the operator must pass over or come into contact with this lever m. At the same time the normal position of the arc h which moves in unison with the lever mis directly in the path of travel of the triprod 8 when the operator touches the treadle, to pressthe same downward, the connecting rod a is immediately brought into action; the rod a being adjustably attached to rod a it is immediately drawn downward pulling therewith the arm k of the clutchmember h assembled on the pinion c. This action of the clutch-member it draws with press. The are .h is adjustable to move in unison with the lever m, and is so adjusted that when the lever m has reached its extreme position the end of the are 7& .has

passed from under the shoulder of the triprod 8; and stands to allow the free movement downward of the trip-rod 8 in' unison with the connecting parts of the rod a. The travel of the lever m and the are k are adjustably limited by the projecting arm h of the collar k while the clutch member in is free to continue its rotation. This permits the treadle to be pressed onward to its downward extreme without further influence upon the clutch member (71, and the By .this arrangement it will be observed that the clutch member k with its assemblage, the lever 77)., and the are k are always free to move, independently of clutch member h, in the event any obstruction is offered to the lever 121. While the parts described are advancing to the positions described, the loose play provided in block 0 permits rod (1 to freely move in blocks 0 and (1 without drawing or influencing the bell-crank-lever N; this loose play is so adjusted that action upon block 0 begins after the lever m is in full vertical protective position. As the treadle continues to be pressed downwardly, if the are its has cleared the path of the triprod 8 the whole assemblage of the connecting rod to the lever N is maintained at a fixed unit (as shown in Fig. 7) and the clutch-pin will be withdrawn to permit the press to be operated. It will be observed (as shown in Figs. 4 and 5) that when the are [L8 has cleared the path of the trip-rod s, and the said rod 8 has begun to descend, the are k is kept in a locked position by its contact with the side of the trip-rod s and thus makes the lever rigidin unison with the position of the arc it -which condition is sustained during the stroke of the press. The relative position of the are k and the trip-rod s has now become an obstruction to the arc h", and since these parts move as a unit the obstruction to are 7L has become an obstruction or lock to the lever 'm. This locked lever is intended to prevent sudden thoughtless or inadvertent moves of the operator during the time of the descent of the plunger (as illustrated in Figs. 4: and 5).

\Vhen the treadle is pressed to its utmost limit, releasing the clutch-pin M, the assemblage of the connecting devices are maintained intact; instantly the clutch-pin is released and the revolution of the eccentric shaft begins, the lug o assembled on the eccentric shaft-coming into contact with the lever t-raises the collar t whichstriking the adjustable nut s on the triprod 8 lifts the said trip-rod and conseqruently breaks the toggle connection be- ;tween 1' and 1" collapsing the toggle at 1;

thereby instantlyelongating the connection between the treadle and the clutch-pin (as shown in Fig. 8) permitting the clutch-pin to immediately return toits normal position and prevent a successive stroke. It will be observed that under these conditions, the treadle is maintained free and movable at. all times, and the clutch-pin M is automatically returned free of the treadle the instant the eccentric-shaft revolves. Thus the press is locked against any danger of successive stroke-irrespective of the position of the treadle orlever m-after each stroke of the press. It will be observed that the lever m is maintained in a rigid position only during the strokes of the press; at all other times it will be seen to be yieldable. Instantly the rod 8' is raised by the lever t at t the toggle connections at r is broken. Immediately the toggle is broken an elongation of the connection between the treadle and the clutch-pin takes place; the clutchpinwhen releasedsprings back into its normal position by means of a spring provided and intended for that purpose (which is no part of my mechanism). When the treadle is released, the spring J returns it to its normal position, and by the same action raises the rod atogether with its assemblagebetween block 0 and block d-causing a spreading of the links r and a dropping into place of the toggle links 7" and 1"; the toggle links 2' and 2' have offset 7' and ends 1- for locking, so adjusted that the links fall to a point just below the center at T or just below the level of the two outer points 2' and 7'. The toggle links in this position form a rigil brace or lock. The slot or loose play provided in the end of the toggle link assists in the instantaneous and positive locking of the toggle and links.

The lever on with itsoperating assemblage to the are it being free to move independently of the other parts of the device it willbe seen that a pressure upon the lever plate m serves to check or hold the arc h under the shoulder s of the rod s-thus obstructing its downward travel. It the treadle is continued to be pressed downwardly the are k maintains the rod 8 in a fixed position, and thus breaks the rigid connection between r and a (as shown in Fig. 8), collapsing the links 1' and increasing the distance between the treadle F and the lever N, resulting in a neutralization of the treadle action, and preventing action upon the lever N. Thus, if the hand is upon the dies, or anywhere within the zone of operation of the press, or in contact with the lever m, the connection between the treadle and the clutch-pin is automatically elongated and the treadle is free to cover its Whole area of travel Without any influence upon the clutchpin M; thus I provide a yieldable protection to the hands; a yieldable treadle action; and

'1 provide a device which automatically subjects the activities of the press to the volition of the operator; He can intentionally stop the activity of the press by intercepting the lever mit he does so at any time be tions of the press-prior to the locked position describe'd-force is brought to bear on the lever m, the action upon the clutch-pin M is prevented! It will thus be seen that claim to secure an automatic method of safe-guarding the operator, different entirely from anything heretofore devised. I do away with the need of alertness and celerity. I do not employ force, nor do I throw the hand out oi the danger-zone; nor do ll depend upon the power of the hand to resist the power of the foot to stop the drawing of the clutch-pin; each acts freely and independently of the other to accomplish its individual purposes, and their united purposes.

of the press-adapted to mechanically vary the distance between the said points during the operation of the press: a secondary lever pivotally attached thereto adapted to present a yielding constructive lever between the operator and the operative zone simultaneously with the functioning of the treadle; a clutch; said obstructive lever linked to a member of the said clutch; said clutch; said obstructive lever linked to a member of, the said clutch; said clutch member provided with an extension adapted to intercept the travel of the toggle-levers, cause their collapse, and thereby effect the variation herein specified.

2. A- safety device for hand-fed power punch presses, wherein the connecting means joining the treadle and the press operating mechanism, consists of a plurality of rods pivotally united by a. plurality of togglelevers, adjusted so as to permit an automatic increase of distance between the extreme points of attachment of the connecting-means; a lever assembled on the bedplate adapted to eiiect the said increased length when any force is applied to move said lever out of a predetermined position.

3. In combination with a hand-fed power punch press, a device constituting the connection between the tre'adle and presscontrolling mechanism consisting of means for automatically increasing the distance between the points specified whereby the travel of the treadle may beneutralized and the normal effect of the treadle upon the press clutch nullified throughout the functioning of the treadle; a protective lever assembled upon the bed-plate adapted to be raised to a predetermined position by the treadle functioning; a trip-lever operated by the aforementioned lever adapted to eitect the increased length of the said connecting mechanism when any force comes into contact with said protective lever--during every functioning of the press, except during the actual time of the descent of the punch; means to maintain said protective lever rigid during the descent of the punch.

4. A safety appliance for the purposes described embodying therein a lever mounted upon the bed-plate adapted to present an unobstructed approach to the punch when press is at rest and to present a yieldable obstructive barrier between the operator and the operative zone when the press is in action; a clutch controlling the movements of the said lever and conversely controlled by|the said lever when any force is brought to bear upon the said obstructive barrier lever; a press connecting rod assemblage adapted to function said clutch and set the said obstructive lever in position of protection to the operator; a leverforming an extension of one member of the said.

clutch-operated by the said obstructive lever-designed to effect a neutralizing of the treadle movement upon the press starting mechanism in the event the hand of the operator is Within the operative zone of the punch.

5. A device of the character described embodying therein a plurality of co6perating toggle levers forming part of the treadle-connecting rod: a trip-lever operated from the bed-plate adapted to intercept the travel of the toggle-levers, alter their relative position and elongate the treadle-rod sufficiently to compensate the normal travel of the treadle.

6. In a device of the character described, a connecting mechanism embodying a plurality of toggle-links held normally in rigid position, one pair of said toggle-links adapted to be forced upwardly'and contract the remaining toggles a predetermined distance; a rod pinioned at the center of the said upwardly acting toggles, having a projecting shoulder; a trip-lever operated from the bed-plate, adapted to project under the said shoulder and efi'ect an "elongation of the connecting mechanism-for the purposes described.

7. A device for the purposes specified, substantially in form described, embodying means to normally maintain the connecting mechanism rigid; a trip-lever operated by a protective guard mounted on the bedplate; means to automatically break the rigidity of the said connecting mechanism and prevent the descent of the punch when any pressure is brought to bear upon the sriid protective guard mounted on the bedp ate. I

8. In combination with a hand-fed power punch press an assemblage connecting the treadle with the press controlling mechanism, embodying asa part thereof, a series of toggle-levers adapted to elongate the distance between the points mentioned: a clutch normally operated by the treadlerod adapted to project a protective yieldable barrier in front of the punch: a yieldsembled on the bed-plate to force it out of a predetern'lined protective position.

9. In combination with a machine of the class described, a safety device substantially in the form described, adapted to automatically present a yieldable protective lever between the operator and the punch prior to the beginning of the descent of the punch; means to lock the protective lever during the descent of the punch; means vcoeval with the descent of the punch to automatically lock the press against a successive stroke; means to maintain the v treadle constantly yieldable throughout the functioning of the press.

10. A safety appliance for the purposes described embodying therein a lever mounted on the bed-plate acting as a protective guard, means actuated by the treadle whereby said protective guard is raised to a predetermined position prior to the beginning of the descent of the punch; means actuated by said protective lever whereby the punch is rendered non-active if the hand of the operator is within the zone of the punchs activity. I

11. A safety appliance for the purposes described embodying therein a lever mounted on the bed-plate acting as a protective guard, means actuated by the treadle whereby said protective guard is raised to a predetermined position prior to the beginning of the descent of the punch; means actuated by said protective lever whereby the punch is rendered non-active ifthe hand of the operator is within the zone of the punchs activity; an emergency actuating means operative from the punch actuating means whereby the punch is locked against a successive stroke until the treadle comes to a normal position of rest and all the protective elements are established.

12. A safety appliance for the purposes described, embodying therein a treadle controlled press clutch actuating mechanism, consisting of means for automatically varying the distance between the treadle and the press clutch actuating mechanism; an emergency means operative from the bed-plate whereby the travel of the treadle is compensated and the normal action upon the clutch is nullified.

13. A safety appliance for the purposes described, embodying therein a treadle controlled press clutch actuating mechanism, consisting of means for automatically varying the distance between the treadle and the press clutch actuating mechanism; an emergency means operative from the bed-plate whereby the travel of the treadle is compensated and the normal action upon the clutch is nullified; means to lock the punch against a successive stroke until the treadle is in a normal position of rest.

14. In combination with a punch press a safety appliance wherein the treadle controlled punch actuating mechanism embodies means adapted to automatically nullify the action of the treadle upon the punch actuating means; a guard lever mounted upon the bed-plate adapted to actuate a trigger, said trigger adapted to actuate the means whereby the action of the treadle upon the punch actuating means in nullified; emergency means actuated by the punch actuating means whereby the punch scribed my name in the presence of two witnesses this 17th day of Dec. 1913.

\VILLIAM BRETSNYDER.

Witnesses ARNI) BRETSNYDER, MARGERY HAINES. 

